This invention relates to a method and apparatus for a passive station to locate itself relative to a pulsed transmitter that radiates a narrow scanning beam. Applications include radio navigation and homing using an existing radar transmitter or dedicated rotating beacons and self-location of receivers in a bistatic or multistatic radar system.
There are presently in existence various devices and methods for a station to locate itself. Some of these are well known, such as the ranging radar which is an active device in that is radiates a pulse and measures the time elapsed for a reflected signal to return from a known location. Using either bearing information or additional information from further known locations the station can locate itself relative to the object or objects. However, because this type of device is active, i.e., it radiates a signal, the device is relatively bulky, requires relatively high power for appreciable ranges and it can be detected and located by a remote station. Another device and method used for self-location is a direction finding antenna using crossed bearings from two or more known-location transmitting station. Where these two or more bearings cross is a measure of the location of the station. However, as indicated above, this method requires two or more transmitting stations.
These, and other known methods and devices have the disadvantage of either requiring bulky, expensive and relatively high power transmitting equipment or requiring two or more known-location transmitting stations. Additionally, an active station when transmitting a signal is susceptible of being located by other stations.
It is therefore one object of the present invention to provide a method for a station to locate itself that is completely passive.
It is another object of the present invention to provide a method for a station to locate itself that is simple, fast and accurate.
It is a further object of the present invention to provide a method for a station to locate itself relative to only one stationary or moving transmitting station.
It is still another object of the present invention to provide a device for a station to locate itself that is completely passive.
It is still a further object of the present invention to provide a device for a station to locate itself that is compact and inexpensive.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.